• Korean journal of food and cookery science
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• v.20 no.6 s.84
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• pp.643-649
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• 2004

Pork was cooked using three kinds of instrument [electric pill (EG) for 5min., microwave oven (MW) for 6min. and reheated using a MW] and then extracted with $80\%$ methanol. The Ames test was performed on the methanol extracts, employing the S. typhimurium tester strain, TA100. The methanol extract of cooked pork showed high mutagenicity ion the 5.0 mg/plate without the S9 mix, but a higher mutagenicity was induced with the S9 mix With increasing refrigeration $(4^{\circ}C)$ and freezing $(-18^{\circ}C)$ periods the extracts showed higher mutagenicities and TBA values, and the same results where shown with reheating. Correlations of the mutagenicity (-S9 mix) and rancidity of the pork cooked by EG, according to storage at and $-18^{\circ}C$ and reheated by MW (1 min), were r=0.85, 0.86, 0.98 and 0.83, respectively. When the MW was used for reheating, the refrigeration storage (r=0.98) showed a higher correlation coefficient than for that stored frozen (r=0.83). From the structure of cooked pork, as observed by SEM, many vapor pathways were viewed in the pork reheated using themicrowave oven.

• Interaction and multiscale mechanics
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• v.2 no.1
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• pp.69-89
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• 2009

Reinforced and prestressed concrete (RC and PC) thin walls are crucial to the safety and serviceability of structures subjected to shear. The shear strengths of elements in walls depend strongly on the softening of concrete struts in the principal compression direction due to the principal tension in the perpendicular direction. The past three decades have seen a rapid development of knowledge in shear of reinforced concrete structures. Various rational models have been proposed that are based on the smeared-crack concept and can satisfy Navier's three principles of mechanics of materials (i.e., stress equilibrium, strain compatibility and constitutive laws). The Cyclic Softened Membrane Model (CSMM) is one such rational model developed at the University of Houston, which is being efficiently used to predict the behavior of RC/PC structures critical in shear. CSMM for RC has already been implemented into finite element framework of OpenSees (Fenves 2005) to come up with a finite element program called Simulation of Reinforced Concrete Structures (SRCS) (Zhong 2005, Mo et al. 2008). CSMM for PC is being currently implemented into SRCS to make the program applicable to reinforced as well as prestressed concrete. The generalized program is called Simulation of Concrete Structures (SCS). In this paper, the CSMM for RC/PC in material scale is first introduced. Basically, the constitutive relationships of the materials, including uniaxial constitutive relationship of concrete, uniaxial constitutive relationships of reinforcements embedded in concrete and constitutive relationship of concrete in shear, are determined by testing RC/PC full-scale panels in a Universal Panel Tester available at the University of Houston. The formulation in element scale is then derived, including equilibrium and compatibility equations, relationship between biaxial strains and uniaxial strains, material stiffness matrix and RC plane stress element. Finally the formulated results with RC/PC plane stress elements are implemented in structure scale into a finite element program based on the framework of OpenSees to predict the structural behavior of RC/PC thin-walled structures subjected to earthquake-type loading. The accuracy of the multiscale modeling technique is validated by comparing the simulated responses of RC shear walls subjected to reversed cyclic loading and shake table excitations with test data. The response of a post tensioned precast column under reversed cyclic loads has also been simulated to check the accuracy of SCS which is currently under development. This multiscale modeling technique greatly improves the simulation capability of RC thin-walled structures available to researchers and engineers.

• Journal of the Korean Chemical Society
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• v.21 no.5
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• pp.330-338
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• 1977

In order to elucidate the plastic deformation of solids, the following assumptions were made: (1) the plastic deformation of solids is classified into two main types, the one which is caused by dislocation movement and the other caused by grain boundary movement, each movement being restricted on a different shear surface, (2) the dislocation movement is expressed by a mechanical model of a parallel connection of various kinds of Maxwell dislocation flow units whereas the grain boundary movement is also expressed by a parallel connection of various kinds of Maxwell grain boundary flow units; the parallel connection in each type of movements indicates that all the flow units on each shear surface flow with the same shear rate, (3) the latter model for grain boundary movement is connected in series to the former for dislocation movement, this means physically that the applied stress distributes homogeneously in the flow system while the total strain rate distributes heterogeneously on the two types of shear planes (dislocation or grain boundary shear plane), (4) the movement of dislocation flow units and grain boundary units becomes possible when the atoms or molecules near the obstacles, which hinder the movement of flow units, diffuse away from the obstacles.Using the above assumptions in conjunction with the theory of rate processes, generalized equations of shear stress and shear rate for plastic deformation were derived. In this paper, four cases important in practice were considered.ted N${\cdot}{\cdot}{\cdot}$O hydrogen bond and the second of two normal N${\cdot}{\cdot}{\cdot}$O hydrogen bonds, both of which exist between the amino group and the perchlorate, groups. A p-phenylenediamine group is approximately planar within an experimental error and bonded to twelve perchlorates: ten perchlorates forming hydrogen bonds and two being contacted with the van der Waals forces. A perchlorate group is surrounded by six p-phenylenediamines and four perchlorates; among the six p-phenylenediamines, five of them are hydrogen-bonded, and the rest contacted with the van der Waals force.

• Korean Journal of Agricultural Science
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• v.9 no.2
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• pp.569-575
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• 1982

Mechanical properties of rice plants were tested to determine compressive force, bending force, tensile force and shear force for improvement of harvesting machines and for efficient utilization of rice culm during the proper harvesting period. Rice varieties used in this study were two Japonica varieties with Irri 348 and Jinju, and two $Indica{\times}Japonica$ hybrids with Seogwang and Taebaeg, which were grown in the standard fertilization field of Chungnam Rural Development Office. Also Jinju and Taebaeg were tested to elucidate the shearing characteristics which included shear force-strain relationship, shear force and shear energy according to the position from the ground level, the shearing angle to the rice culm, and the moisture content. 1. Compressive force, bending force, tensile force and shear force were higher In Japonica varieties than $Indica{\times}Japonica$ hybrids. 2. Shear force to overall culm length decreased progressively to upper positions in Jinju variety but a constant shear force was approximately showed between the ground level and the position of 21cm in Taebaeg variety. 3. Shear force and shear energy increased with increase of the cross sectional area, and the rates of increase were high in general up to the cross sectional area of $10mm^2$ and then they became dull very much. 4. Shear force and shear energy decreased with decrease of moisture content of rice culm after cutting up to the moisture content of 60% (w. b.) and then they did not change significantly.

• Development and Reproduction
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• v.5 no.2
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• pp.151-158
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• 2001

Genomic DNA from the blood of crucian carp(Carassius carassiu) from lake and aquaculture facility in Kunsan, Korea was extracted in order to identify genetic differences by polymerase chain reaction-randomly amplified polymorphic DNAs(PCR-RAPD). Out of 12 primers, 6 generated 266 highly reproducible RAPD markers, producing approximately 2.1 polymorphic bands per primer in crucian carp from lake. The degree of similarity varied from 0.18 to 0.76 as calculated by bandsharing analysis in crucian carp from lake. The RAPD outlines obtained with DNA of two different crucian carp populations from Kunsan were different(0.47 from lake and 0.70 from aquaculture facility, respectively). The electrophoretic analysis of polymerase chain reaction-randomly amplified polymorphic DNAs(PCR-RAPD) products showed high levels of similarity between different individuals in crucian carp from aquaculture facility. This result implies the genetic similarity due to raising in the same environmental condition or inbreeding within the crucian carp from aquaculture facility in Kunsan. In other words, crucian carp may have high levels of genome DNA diversity due to the introduction of the wild population from the other sites of Knsan even if it may be the geographical diverse distribution of this species. Generally, the RAPD polymorphism generated by these primers may be useful as a genetic marker for strain or population identification of important aquacultural fish species, crucian carp. However, in future, additional populations and sampling sites will be necessary to complement weak points.

• Journal of Dairy Science and Biotechnology
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• v.34 no.2
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• pp.137-144
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• 2016

The ultimate research goal of the current study was a development of hydrolyzed whey protein powder (7%-GNANA) manufactured with normal content of sialic acid, a marker compound, that is naturally occurring at 7% concentration in GMP obtained from the milk protein. GMP is a safe food, used worldwide in infant and baby foods, etc. The test substance was prepared using (7% sialic acid containing) GMP as a raw material, and then using alcalase, an enzyme approved as a food additive, after separation of sialic acid with 100% efficiency and 7%-GNANA (containing 7% sialic acid and protein; product name: HELICOBACTROL-7) provided by MEDINUTROL Inc. (Korea). Bacterial reverse mutation (Ames) test was conducted in accordance with GLP Guideline using the test substance specified above. To identify its mutagenic potential against microorganisms, histidine auxotrophic strains of Salmonella Typhimurium, TA98, TA100, TA1535, and TA1537, and tryptophan auxotrophic strain of Escherichia coli, WP2uvrA, were used. The bacterial reverse mutation (Ames) test was performed by dividing the test substances into five different concentration groups (0, 61.7, 185, 556, 1,670, $5,000{\mu}g/plate$). Results of this experiment did not reveal repetitive increase of colony generating values or positive criteria for reverse mutagenicity for any concentration of test substances in any of the five strains, regardless of the presence of a metabolic activation system, and no dose-dependency was identified. In conclusion, the safety of 7%-GNANA test substance was verified by bacterial reverse mutation test conducted before registration of 7%-GNANA as a food additive.

• Korean Journal Plant Pathology
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• v.3 no.3
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• pp.223-235
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• 1987

Samples showing yellow mosaic symptom of Lilium spp. with necrotic fleck, stunting, malformation, and colour breaking were collected from lily-growing areas in the southern part of Korea. Two viruses were distinguished under a electron microscope and their host range, serological reaction, stability in sap, type of aphid transmission, and relations with cells and tissues were examined. Broad bean wilt virus (BBWV) was transmitted by sap-inoculation to 23 plant species in 8 families and by the aphid, Myzus persicae. This virus was inactivated after 10 min at 70C, at dilution of $10^{-3}$, and after 6 days at about 20C. Electron microscopic examination of purified preparation showed that the virus is spherical particle of 28nm in diameter. The virus reacted positively with BBWV-antiserum in agar gel diffusion test. In ultrathin sections of BBWV infected tissues, large aggregates or crystalline array of virus particles and vesicular body were found in the cytoplasm, vacuole, and nucleus of mesophyll cells. Cucumber mosaic virus (CMV) was transmitted by sap-inoculation. Electron microscopic examination of its purified preparation showed spherical particles of 30nm in diameter. The virus reacted positively with CMV-Y strain-antiserum in agar gel diffusion test. In ultrathin sections of CMV infected tissues, crystalline array of virus particles were found in the vacuole and a large number 0f virus particles were found in the cytoplasm and the plasmodesmata of mesophyll cells. When each of these viruses was retransmitted to Lilium tigrinum. L. concolor, and L. auratum, BBWV induced slight symtoms and colour breaking, but CMV induced yellowing mosaic or necrotic fleck.

• Food Science of Animal Resources
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• v.26 no.4
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• pp.503-510
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• 2006

Survival and stability of 19 bifidobacterial strains included 13 isolates from Korean infants against acid, bile acid and oxygen exposure were examined. Acid resistance of selected strains at pH values of 4.0, 3.0 and 2.0 was tested. Among the bifidobacterial strains tested, B. bifidum B3, B. longum D6, and B. adolescentis F1 exhibited higher viable cell counts exposed to acid whereas other strains had various results. The abilities of the strains to grow in the MRS broth containing 0.2% thioglycolic acid and 0.2% oxgall were tested and the tolerance of B. bifidum B3 and B. longum D6 to bile acid were higher than that of others. Even though in same species, the tolerance of tested strains to bile acid were variable. Stabilities of tested strains to oxygen exposure were variable and B. bifidum and B. longum strains showed relatively higher viable cell counts after 48 hours exposure to aerobic incubation. These results demonstrated that the survival and stability of bifidobacterial strains to acid, bile acid, and oxygen exposure were variable and strain-dependent. Due to their tolerant ability to environmental factors like acid, bile acid, and oxygen, B. bifidum B3 and B. longum D6 had good potential properties as probiotic cultures and may be useful for industrial application.

• Journal of the Korea Concrete Institute
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• v.29 no.2
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• pp.189-200
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• 2017

Nonplanar structural walls with C-shaped and H-shaped sections have been used as an efficient lateral force-resisting system for building structures. Since the nonplanar walls are subjected to axial load and bending moments about two orthogonal axes, complicated section analysis is required for flexure-compression design. In the present study, a straightforward design method for biaxially loaded C- and H-shaped walls was proposed by modifying the existing load contour method for columns with symmetric solid sections. For this, a strain compatibility section analysis program that can calculate biaxial moment strengths of arbitrary wall section was developed and its validity was verified by comparing with existing test results. Then, through parametric study, the interaction of biaxial moments at constant axial loads in prototype C- and H-shaped walls was investigated. The results showed that, due to unsymmetrical geometry of the wall sections, the biaxial interaction was significantly affected by the moment directions and axial loads. From those investigations, non-dimensional contour equations of the biaxial moments at constant axial loads for C- and H-shaped walls were suggested. Further, design examples using the proposed contour equations were given for engineering practice.

• Journal of Environmental Health Sciences
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• v.14 no.2
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• pp.73-87
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• 1988

This study was performed to investigate the effect of lactose in 4 different concentrations against the protective effect of calcium on the acute lead poisoning in rats after 4 weeks treatment. In this animal experiment, 70 albino male weanling rats (50-70g of body weight) of Sprague-Dawley strain were used. Lead was dissolved in the distilled water and intubated at the dose of 400mg lead (as acetate)/ kg of body weight/day. Calcium and lactose were administered in drinking water ad libiturn dissolved with the solution of 0.7% calcium gluconate mixed with 40, 80, 160 and 320mM lacotse respectively. The results obtained were summarized as follows: 1. The rate of body weight gain in all treated groups turned out to be lower than that in the control group during 4 weeks treatment. The slow-down of body weight gain was the most significantly observed in the group treated with lead only ( p < 0.05). 2. The relative spleen weight in lead only treated group was significantly lower than that of lead + calcium, lead + calcium + 80mM lactose treated group ( p < 0.05). 3. The value of RBC, WBC, Hb and Hct showed a decreasing tendency in the group treated with lead only ( p < 0.05), however, a significant decrease was not observed in the group treated with lead + calcium. On the other hand, the protective effect of calcium was deteriorated in the group treated with lead + calcium + lactose. 4. The activity of $\delta$-aminolevulinic acid dehydratase ($\delta$-ALAD activity) showed the same tendency as No. 2. 5. The lead concentration in the blood (PbB) showed an increasing tendency and the interrelation among the different groups was also identical with No. 2. 6. With a statistical approach, it was found out that the activity of $\delta$-ALAD and the lead concentration in the blood show a relation of inverse proportion(r=-0.7301). The diagram was interpreted with the logarithmic equation InY = 5.5357-0.0251X (X:PbB, Y:$\delta$-ALAD activity). 7. In the histopathological findings of the kidney, the protective effect of calcium was observed. However, the protective effect of calcium was restricted in the group treated with lead + calcium + lactose. As a conclusion, the intensity of the acute ingested lead poisoning was obviously reduced by calcium, however, the protective effect of calcium was deteriorated in proportion with the concentration of the lactose to be administered. On the other hand, it was also noted that the deterioration was lightly restrained in the group treated with the physiological concentration of 80mM lactose than the results shown in the groups treated with lactose of other concentrations.